The overall goal of this program project is the study of molecular mechanisms which sustain and promote the growth of lympho-reticular and hematopoietic neoplasms as well as modulate potential therapeutic approaches such as bone marrow transplantation. All of these diseases have profound structural consequences in the host. Thus, any study of these neoplasms must include an accurate morphological assessment of their anatomic consequences. The broad scope of these projects requires an array of morphological capabilities. However, their interdependence and overlapping nature mandates a high degree of consistency in the technical and interpretive components of any morphological assessment. The most efficient means of achieving the desired level of technical competence and interpretive consistency is through the establishment of a core histology laboratory dedicated to the support of the anatomic pathology needs of this program project. This laboratory should be equipped with quality, cost efficient materials and instruments, staffed by a highly competent histotechnologist and directed by a pathologist well qualified to provide administrative oversight and consistent, accurate interpretation of all results produced within the laboratory. This description of the role of the histology core laboratory will describe the services to be provided, a budget to produce cost effective, high quality technical services, and evidence as to the qualification of Dr. Jennings to provide administrative and interpretive services to this program project. The technical mission of the histology core laboratory is to provide high quality tissue sections for the individual research protocols in a timely and cost effective manner. As designed, the budgeted equipment and supplies will allow the provision of traditional hematoxylin and eosin stained paraffin embedded tissues, immunohistochemistry staining of both paraffin embedded and frozen sectioned tissues, and TUNEL assays for detection of apoptotic changes. The hematoxylin eosin staining, basic immunohistochemistry, and TUNEL assays will be provided through the core laboratory support at no additional charge to the individual research protocols. The ability to batch particular runs after dilutions of reagents have been made will result in substantial savings over purchasing these assays from the hospital histology lab or a commercial laboratory. Further, having a dedicated histology facility will expedite turn-around-time of results to individual researchers as compared to the hospital histology laboratory that appropriately gives priority to patient care work and is presently running at both a space and labor saturation point.